This week negotiations are expected to resume in Geneva for an interim accord to freeze Iran’s nuclear enrichment and heavy water programmes while a more comprehensive agreement is pursued. These negotiations will involve representatives of the permanent members (P5) of the UN Security Council, plus Germany, and the government of Iran. As Wednesday’s talks approach, there are four important points we should bear in mind.

First, these negotiations demonstrate what can be accomplished by a united front among the US, Britain, France and Germany. Apart from the EU sanctions against Iran, this has made possible the important use of the UN Security Council, whose resolutions establishing an increasingly powerful sanctions regime would never have been possible without Western unity.

There are substantial incentives to depart from that unity. The Israeli prime minister, Binyamin Netanyahu, has already denounced the Obama administration’s initiative and some members of the US Congress are pressing for additional sanctions on Iran, which at the least would complicate the negotiations. Similarly, France’s position has reflected the anxieties of Saudi Arabia and other Gulf states, and the French foreign minister undermined a tentative accord last week by insisting that construction of a heavy water reactor — an additional source of nuclear grade material — be stopped before further negotiations took place. Despite these pressures, the Western states and their P5 colleagues seem so far to have held together all these many months, an achievement perhaps as significant for the future as any particular agreement that may emerge.

Second, we should remain aware that there are two quite different approaches to these negotiations within the P5+1. One approach holds that the next step must be to build confidence among the negotiating parties and that this can be achieved by relatively modest initial agreements which, if pursued by both sides in good faith, could yield the first steps in a decade to halt Iran’s nuclear programme. We should remind ourselves that in that decade, Iran’s enrichment programme has grown from a single cascade of 164 centrifuges to more than 10,000. A failure to win an accord would allow Iran to continue expanding its programmes.

A different approach, however, sees incremental steps as legitimating Iran’s progress toward a nuclear arsenal. It even suggests that the current round of exchanges is only an extension of the tactics of buying time that have brought Tehran to the verge of a nuclear breakout capability. Using the 10,000 centrifuges that Iran currently operates — some estimates are as high as 19,000 — it is generally thought that while it would have taken more than six months to produce sufficient fissile material for one weapon from natural uranium 238 — or even enriched to five per cent uranium 235 — it may take only about 20 days beginning with the 20 per cent-enriched material Iran now possesses. It will not be easy to reconcile these approaches unless Iran makes concessions that at present seem most unlikely.

Third, there is no point in public calls for a deal that the negotiating parties can never sell to their domestic constituencies. Although there is little legal basis in international law for Iran’s claim that the Nuclear Non-proliferation Treaty provides signatories with an unfettered “right to enrich”, this position seems to have achieved a general consensus within Iranian public opinion. It is extremely unlikely that the Iranian leadership could justify its pursuit of a costly breakout capability by wholly renouncing that option.

The US also must contend with its public. It is hard to see how the President could sell any agreement that did not yield highly intrusive International Atomic Energy Agency (IAEA) inspections, a complete stand down of the plutonium heavy water project, some credible hedge against break-out — something like a 12 months development leash should Iran expel the IAEA and dash for a weapons capability — and some check on the clandestine maintenance of undisclosed nuclear facilities.

Fourth, and most importantly, we must not lose sight of our long-term objectives for negotiations. Isolating Iran may be a reasonable strategy but it won’t be achieved with Iran’s co-operation. What we should be aiming for is a de-nuclearisation of the region. It is telling that Israeli public opinion supports such denuclearisation even while it remains deeply sceptical of Iranian intentions.

With the Saddam Hussein regime out of the picture, it is now possible to pursue such denuclearisation, as it never could have been while Iraq remained in Saddam’s thrall. This goal ought to be the standard by which all our interim steps are measured. We should always bear in mind that, as Nietzsche remarked, forgetting our objectives is the most frequent act of stupidity. Simply halting further Iranian nuclear development for a time is not a long-term strategic goal.

It is not difficult to foresee that, if Iran is not stopped in its pursuit of a nuclear weapons capability, Saudi Arabia and perhaps other states in the region will quickly follow suit. In such an eventuality the possibilities of an apocalyptic conflict will cast a long shadow over the politics of the Sunni/Shia conflict now roiling so many societies and the increasing isolation of Israel.

But this is not inevitable. Given the increasing accuracy — and thus lethality — of conventional weapons, there is no reason why security guarantees to the states of the region could not insure a denuclearised future.

It is sometimes forgotten that the most important developments in non-proliferation have not been in Libya or South Africa but in Germany and Japan, two states that faced mortal threats and had the technology and the wealth to deter those threats through the acquisition of nuclear weapons. That that didn’t happen is an underappreciated triumph of the alliance of the democracies that challenged the Soviet Union. There is a similar role in the fraught region of the Middle East to be played by the members of that alliance and the successors to the regimes of the Cold War they fought.